Desiccants are used to manage uneven crop maturity and weed escapes in beans, to improve seed quality. Glyphosate has been a popular choice, but there is a risk of herbicide residues in the seed if it is applied too early. The purpose of this study was to compare new herbicides for crop and weed desiccation in Canada.
A total of 11 field studies were done at Lethbridge AB, Carmen MB and Exeter ON in 2010-2012. Reglone (diquat), Aim (carfentrazone-ethyl), Ignite (glufosinate ammonium), Valtera (flumioxazin) and Eragon (saflufenacil) were tested alone, and in combination with glyphosate. All treatments were applied when 80% of the pods had changed colour. Leaf, stem and pod desiccation, weed desiccation, seed moisture and yield were measured.
None of the desiccant treatments affected crop yield (data not shown). Reglone and Ignite were strong crop desiccants, and they had high scores for all weed species tested (Figure 1). Eragon was the best crop desiccant but it was weak on lambsquarters and foxtail. Valtera was a strong desiccant but it was weaker on most weeds. Aim was a weaker crop desiccant, and it was weak for all four weed species. Glyphosate was a weak crop desiccant, but it was strong on foxtail. Adding glyphosate to each desiccant improved the consistency of performance of each herbicide (data not shown).
Originally published in Canadian Journal of Plant Science 2013. Volume 93. Pages 871-877. Updated in July 2020 for drybeanagronomy.ca.